Tapped delay equalizers are well known in pertinent signal processing technologies as being an effective means for shaping electrical signals. They are widely used in a variety of electric/optical environments, and they are employed for a plethora of different purposes. For the present invention, the electrical/optical environment of interest involves the transmission of optical signals over a fiber optic. Accordingly, a purpose here is to provide an effective driver chip for use in a system that includes Electrical/Optical (E/O) and Optical/Electrical (O/E) converters, which will optimize the quality of signal transmissions.
From a system perspective, it happens there are many ways in which a signal can be distorted and corrupted as it is being processed and transmitted. To some extent, but not entirely, the source and effect of these distortions and corruptions (i.e. impairments) are known, or can be predicted. Thus, they can be at least partially compensated for. For instance, these impairments can include: 1) transmission line losses, along with impedance mismatch distortions such as InterSymbol Interference (ISI) that can be introduced at interfaces between system components (e.g. driver chip, E/O converter, fiber optic, and O/E converter); 2) electrical and photonic signal distortions caused by impairments such as amplitude and group delay distortions, photon-carrier lifetime effects, and fiber dispersion; and 3) other additional impairments from signal characteristics that can be attributed to slow rise/fall time and laser relaxation peak effect and E/O device parasitics. The present invention, however, recognizes that all of the various impairments noted above can be collectively compensated for by the employment and proper configuration of an analog tapped delay equalizer.
The present invention also recognizes that an “eye diagram,” of a type well known in the pertinent art, can be used to monitor the design, the signal-to-noise ratio (SNR), and the testing or reconfiguration of an analog tapped delay equalizer. When monitored, an optimal operation for the driver chip is indicated when the “eye” of the eye diagram is open to its greatest extent.
With the above in mind, it is an object of the present invention to provide a system and method for simultaneously minimizing operational and architectural impairments during the transmission of an optical signal over an optical fiber. Another object of the present invention is to establish tap weights for the tapped delay equalizer of a driver chip that can be controlled to minimize impairments and distortions to an output signal that are caused by transmission line losses and impedance mismatches, as well as other electrical and photonic impairments. Another object of the present invention is to optimize bandwidth and ISI performance. Yet another object of the present invention is to provide a driver chip for use in optimizing the transmission of an optical signal over an optical fiber that is easy to use, is simple to implement, and is comparatively cost effective.